Coniacian (Late Cretaceous) echinoids from the southern Tethyan shelf (NE Algeria) with remarks on their palaeobiology and palaeobiogeography

Abstract

Thirteen echinoid taxa from Coniacian marl-limestone alternations in three sections south and east of Djebel Metlili, on the southwestern margin of the Aures Mountains in northeastern Algeria, are described: Rachiosoma rectilineatum, Phymosoma tamarinense, Phymosoma cf. mansour, Gomphechinus meslei, Coenholectypus serialis, Coenholectypus subcrassus, Parapygus coquandi, Petalobrissus trigonopygus, Petalobrissus rimula, Hemiaster sp., and Mecaster fourneli. Two taxa are newly described herein, Orthopsis metliliae sp. nov. and a new genus and species referred to the family Phymosomatoidae is erected here, Triboporus luluatus gen et sp. nov. A large amount of well-labeled material, comprising 579 specimens, was collected, with the fauna being dominated by the spatangoid Mecaster fourneli. The fauna exhibits typical characteristics of the Tethyan realm at the genus level; however, at the species level, most taxa are restricted to Algeria, with some also found in adjacent countries such as Tunisia and Egypt. The biostratigraphic framework relies on ammonites and inoceramids, indicating a lower to middle Coniacian age.